Ferromagnetic materials, such as ferrite ceramic materials, continue to experience widespread use in the formation of magnetic recording transducer heads, particularly those used for magnetic tape recordings. Designers and manufacturers of helical scan (4 mm and 8 mm), quarter inch cartridge (QIC) and half inch linear streaming tape drives continue to find ways to extend the life of ferrite recording head technology. One reason behind this drive to extend the life of ferrite recording head technology is the considerable capital investment, worldwide, in the manufacturing technology and processing equipment, as well as the cost effectiveness and reliability experienced when using wear-resistant ceramic materials with known abrasion and wear characteristics in tape contact recording.
Originally, most ferrite-based head transducers used in disk (fixed and floppy) and tape drives employed discrete heads formed of polycrystalline ferrite. Subsequently, single crystal and metal-in-gap (MIG) technologies were introduced and refined. For example, today's DLT.TM. streaming tape drives employ advanced ferrite head transducers which have improved an order of magnitude over the 12 year life of the DLT.TM. product line. The current ferrite heads employ a single crystal material which reduces noise and increases frequency response over polycrystal ferrite head designs. MIG technologies have also improved data writing.
Even more recently, multi-channel head arrays have been formed out of undivided bars of ferrite which have been precisely machined to provide precise head-to-head alignment of the type needed for record/playback compatibility on different tape drives of the same or compatible design. The present inventor has developed self-aligned multiple channel head assembly for tape drives. Plural ferrite head regions were precisely machined from a single elongated ferrite bar in a manner realizing self-alignment and efficient use of materials with low manufacturing costs. Examples of this prior development are set forth in commonly assigned, copending U.S. patent application Ser. No. 08/899,082 filed Jul. 23, 1997, entitled: "Method and Apparatus for Multiple Channel Head Assembly" (File Wrapper Continuation of earlier application Ser. No. 08/507,618 filed on Jul. 26, 1995, now abandoned). The disclosure of this application is incorporated herein by reference.
It is known to employ soft magnetic metal alloy materials formed of iron and aluminum as core structures for tape heads. Alfenol (84 percent Fe, 16 percent Al), Sendust(85 percent Fe, 6 percent Al, 9 percent Si, also referred to as Spinalloy), and Vacodur (similar to Alfenol but more workable) are examples of very hard and brittle soft magnetic materials which have been formed and used as head cores. U.S. Pat. No. 4,894,742 to Saito et al. entitled: "Thin-Film Laminated Magnetic Heads of Fe--Si--Al Alloy"; and, U.S. Pat. No. 5,610,786 to Tokutake et al. entitled: "Magnetic Head Having CAO-TIO2-NIO Ceramic With Specified CAO/TIO2 Ratio", and U.S. Pat. No. 4,772,967 to Okuda et al. for "Magnetic Recording Apparatus in a Helical Scan System" set forth examples of single channel heads including alloy films. The disclosures of these patents are incorporated herein by reference.
A common method of fabricating metal thin film heads comprises the steps of sputtering a metallic magnetic thin film on a non-magnetic substrate such as glass or non-magnetic ceramic, followed by successive lamination of alternating layers of magnetic film and non-magnetic insulation to form a laminar head core structure manifesting minimized eddy current. A second substrate, such as glass or non-magnetic ceramic, is then bonded to the laminar core structure to form a sandwich construction. The head structure is completed by winding a coil of wire around a segment of the magnetic core. The number of magnetic films and layers is determined to handle the desired flux density at the head gap with minimized unwanted eddy currents in the core structure. One drawback of this approach shown in the referenced patents is that it is difficult to align the resultant discretely formed heads within a multi-head structure with sufficient precision required for high track density and repeatability from tape drive to tape drive.
A hitherto unsolved need has remained for a precisely-aligned multi-channel tape head with vastly improved high frequency performance while employing existing head array manufacturing technology and consequent cost efficiencies.